JPH0529585B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a flow rate control device that is applied to a power steering device or the like of an automobile and adjusts the flow rate of working fluid supplied from a power source to the power steering device or the like to a predetermined flow rate. .

(Prior Art) An oil pump, which serves as a power source for supplying working fluid to a power steering device that uses fluid as a working medium to assist manual steering torque, is usually rotationally driven by an internal combustion engine installed in a vehicle. As the rotation increases, the discharge flow rate increases.

However, the flow rate required for power steering operation must be ensured in a relatively low speed range of the engine, as the operation only needs to function sufficiently when the vehicle is stopped or when driving at low speeds, and it must be secured at high speeds. It doesn't need much. Therefore, the excess flow rate generated by high-speed rotation is normally bypassed by a flow control valve and returned to a reservoir tank or the like.

Here, as this type of flow rate control valve, the present applicant has installed a main orifice 3 that communicates with an introduction passage 2 that leads oil discharged from a pump 1, as shown in FIG.
Variable orifice sub-orifice 4 arranged in series with this
The sub spool 8 is generated before and after the main orifice 3 by communicating with the power steering device 5 through the sensitive orifice 6 and the oil passage 7 and applying the pressure before and after the main orifice 3 to the sub spool 8, respectively. A flow control device is provided in which the sub-orifice 4 is controlled in response to the differential pressure, and the main spool 9, which is responsive to the differential pressure generated before and after the sub-orifice 4, is matched with a drain passage 10 leading to a reservoir tank (not shown). is suggesting.

The discharge flow rate characteristics of this flow rate control device are as shown in FIG. Due to the increase in the differential pressure before and after passing through the sub-orifice 4, the main spool 9 is moved to the right against the spring force of the balance spring 11 to open the drain passage 10, and a part of the main spool 9 opens the drain passage 10. 10
run away to Thus, the power steering device 5
The hydraulic oil sent to the
Keep it at 1. When the pump discharge rate increases further,
As a result, the main spool 9 moves further to the right, and the increase in the differential pressure generated before and after the main orifice 3 causes the sub spool 8 to move towards its balance spring 1.
Move the sub-orifice 4 to the left against the spring force of 2.
Narrow down. Through this series of operations, the flow rate sent to the power steering device 5 gradually decreases from a constant flow rate Q1 and is mainly controlled by the flow rate Q2 brought about by passing through the sub-orifice 4, so-called flow down control.

By the way, in the conventional example, when the main spool 9 moves, the pump discharge oil passes through the main orifice 3 having a fixed throttle and escapes into the drain passage, so the resistance caused by the main orifice 3 is absorbed into the introduction passage. The pressure in pump 2 increases and pump 1
are forced to do unnecessary work. In addition, the hydraulic pressure acting on one side of the sub-spool 8 is applied to the sensitive orifice 6.
Since the sub-spool 8 is guided from the upstream side of the main orifice 3 through the sub-spool 8, it is susceptible to fluctuations in the pulsation pressure of the pump 1, which is inconvenient when performing delicate flow control.

(Object of the Invention) The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a flow rate control device that can reduce the burden on the pump, prevent vibrations of the spool, and obtain stable flow characteristics. purpose. Another object of the present invention is to provide a flow rate control device that allows a wide selection of connection modes to an actuator such as a power steering device to which a controlled flow rate is guided.

(Summary of the Invention) In order to achieve this object, in the present invention, a main spool for controlling the flow rate of excess oil is slidably accommodated in a main spool accommodation hole through which a hydraulic oil introduction passage and a drain passage open. The inside of this accommodation hole is divided into a primary pressure chamber and a secondary pressure chamber, and the other end of the hollow connector faces the primary pressure chamber and has a discharge hole at one end for guiding hydraulic fluid to the actuator. The connector has a communication hole in its hollow interior that communicates with the discharge hole, and a large diameter part and a small diameter part, with the large diameter part opening into the primary pressure chamber and the small diameter part facing the communication hole. and a sub-spool accommodation hole located in the body, and a passage communicating the introduction passage and the inside of the sub-spool accommodation hole on the large-diameter side thereof, and A hollow sub-spool with a large-diameter part and a small-diameter part corresponding to the large-diameter part and small-diameter part of the sub-spool accommodation hole is slidably inserted into the sub-spool, and the large-diameter side of the sub-spool is One end of the sub-spool faces the primary pressure chamber, and as the sub-spool slides between the outer diameter of one end of the sub-spool and the inner diameter of the large-diameter portion of the connector, the sub-spool is introduced from the introduction passage into the primary pressure chamber. A first orifice is formed to change the amount of squeezed hydraulic fluid to be squeezed, and the inside thereof is located downstream of the first orifice via a damping orifice between the small diameter part of the connector and the large diameter part of the sub-spool. A damper chamber communicating with the connector is formed, and a main orifice is provided in the hollow interior of the sub-spool to guide the hydraulic fluid that has passed through the first orifice to communicate with the communication hole of the connector. A variable throttle sub-orifice is provided in the oil passage between the communication hole and the main orifice, and the discharge pressure of the pump is introduced into the introduction passage, and the first orifice is provided in the primary pressure chamber. By guiding the pressure of the hydraulic oil that has passed through the main orifice and the sub-orifice into the secondary pressure chamber, a differential pressure before and after the main orifice is applied to the main spool, and this differential pressure is By increasing the opening area of the drain passage, the main spool spring urges the main spool to counter this differential pressure, and furthermore, the discharge pressure of the pump is introduced to the introduction passage. A differential pressure between the first orifice, the main orifice, and the sub-orifice is applied to the sub-spool, and by increasing this differential pressure, the degree of constriction of the sub-orifice is strengthened, and the first orifice is
The configuration is such that the degree of constriction of the orifice is relaxed and the sub-spool spring is biased to counteract this differential pressure.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 3 is a sectional view showing an embodiment of the present invention. In other words, the required flow rate of the hydraulic oil discharged from the pump 21 is guided to an actuator (not shown) such as a power steering device, and the surplus flow rate with respect to the required flow rate is returned from the drain passage 22 to the reservoir tank 23 etc. This is a control device, and the housing 24 is formed with a housing hole 26 with one end open, into which a hydraulic oil introduction passage 25 and a drain passage 22 are opened, and a main spool 27 for controlling surplus flow rate is provided in the housing hole 26. The housing hole 26 is housed so as to be slidable in the axial direction, and the inside of the housing hole 26 is divided into a primary pressure chamber 28 and a secondary pressure chamber 29. 3
0 is a hollow connector screwed and fixed to the open end of the accommodation hole 26, and one end of this connector 30 is provided with a discharge hole 31 for guiding hydraulic fluid to the actuator, and the other end faces the primary pressure chamber 28. It's open. Further, this connector 30 is provided with a communication hole 32 communicating with the discharge hole 31 and a sub-spool accommodation hole 33 in its hollow interior.
This sub-spool accommodation hole 33 consists of a large diameter part 33a and a small diameter part 33b, with the large diameter part 33a located on the primary pressure chamber 28 side and the small diameter part 33b connected to the communication hole 32. Furthermore, in the body of the connector 30,
A passage 34 that communicates the introduction passage 25 and the inside of the sub-spool accommodation hole 33 on the large diameter portion 33a side thereof.
is provided. In addition, in this embodiment, the connector 3 in the portion corresponding to the passage 34
The hollow interior of 0 is enlarged in diameter to facilitate the inflow of hydraulic oil from the passage 34.

Inside the sub-spool accommodation hole 33, there are a large diameter part 33a and a small diameter part 33b of this sub-spool accommodation hole 33.
Large diameter portion 35a and small diameter portion 35 corresponding to
A hollow sub-spool 35 with a diameter b is slidably inserted into the large-diameter portion 3 of the sub-spool 35.
One end of the sub-spool 5a faces the primary pressure chamber 28, and as the sub-spool 35 slides between the outer diameter of the one end side of the sub-spool 35 and the inner diameter of the large-diameter portion 33a of the connector 30, the primary pressure is removed from the introduction passage 25. A first orifice 36 is formed to change the throttle amount of the hydraulic oil introduced into the pressure chamber 28, and a damper chamber 37 is formed between the small diameter portion 33b of the connector 30 and the large diameter portion 35a of the sub spool 35. There is. This damper chamber 37 communicates with the downstream side of the first orifice 36 via a damping orifice 38, and a sub-spool spring 39 is housed therein, so that the sub-spool 35 is connected to a stop means (pin) 40. It is biased towards the target. In addition, the damping orifice 38
Since it is sufficient that the damper chamber 37 is communicated with the downstream side of the first orifice 36, this can be connected to the inner diameter of the small diameter portion 33b of the connector 30 and the sub spool 3.
It is also possible to form the fitting gap between the outer diameter of the small diameter portion 5 and the outer diameter of the small diameter portion 35b.

A main orifice 41 is provided in the hollow interior of the sub-spool 35 and is arranged in series with the first orifice 36 to guide the hydraulic fluid that has passed through the first orifice 36. 30 communicating holes 32 . In addition, in this embodiment, a through hole 42 is formed in the body of the large diameter portion 35a of the sub spool 35 in a direction perpendicular to the axis between the pump discharge oil introduction passage 25 and the communication hole 32 of the connector 30. , and a piece 33a' of the large diameter portion 33a of the connector 30, a sub-orifice 43 with a variable aperture is formed parallel to the main orifice 41.

The housing 24 is provided with a passage 45 in which the diagonal hole 44 provided in the connector 30 is connected, and the pressure in the communication hole 32 of the connector 30, that is, the pressure downstream of the main orifice 41, is transferred to the secondary pressure chamber 2.
Lead to within 9. Further, a main spool spring 46 is housed in the secondary pressure chamber 29, and biases the main spool 27 toward the primary pressure chamber 28, that is, toward the left in the figure.

Further, a nipple 48 having a flow path 47 facing the discharge hole 31 provided therein is attached to the connector 30 with a plug 49 that enables screw connection, and is sealed with seals 50a and 50b. A stop is applied. Although the nipple 48 is directed downward in the illustrated state, its orientation can be changed by loosening the screwed plug 49 to facilitate piping to an actuator such as a power steering device.

Note that 50c is a seal ring.

With the flow rate control device having such a configuration, the same discharge rate characteristics as shown in FIG. 2 can be obtained. That is, substantially the entire amount of the hydraulic oil led from the pump 21 to the introduction passage 25 passes through the first orifice 36, the main orifice 41, and the sub-orifice 43 in the low discharge region of the pump 21, and is sent to the actuator. When the pump discharge rate increases and the flow rate passing through the main orifice 41 increases, the differential pressure generated before and after the main orifice 41 causes the main spool 27 to be moved by the main spool spring 4.
Move the drain passage 22 to the right against the spring force of 6.
Open to let some of the hydraulic oil escape. In this way, the hydraulic fluid sent to the actuator is maintained at a constant flow rate Q1 based on control by the first orifice 36, main orifice 41, and sub-orifice 43. When the pump discharge rate further increases, the opening area of the drain passage 22 increases due to further rightward movement of the main spool 27, and at the same time, the differential pressure generated before and after each orifice 36, 41, 43 increases, and this differential pressure causes Hold the sub spool 35 to the sub spool spring 39.
Move the sub-orifice 4 to the left against the spring force of
Narrow down to 3. Therefore, the hydraulic fluid sent to the actuator gradually decreases as the sub-orifice 43 is constricted, and is finally limited to the flow rate passing through the main orifice 41, reaching the flow rate Q2 shown in FIG. Note that the pressures inside the introduction passage 25, the primary pressure chamber 28, and the sub-spool 35 have the following relationship: introduction passage 25>primary pressure chamber 28>inside the sub-spool 35.

Here, the sub-spool 35 is urged rightward in the figure by the pressure on the discharge hole 31 side, and leftward by the pressure of the introduction passage 25 and the primary pressure chamber 28, so that the amount of oil discharged from the pump is In order to operate the sub-spool 25 and throttle the sub-orifice 43 to start flow rate control when the predetermined amount is reached, the pressure biased in the left direction may be increased.
Therefore, a first orifice 36 that causes flow resistance when the amount of pump discharged oil is low between the introduction passage 25 and the primary pressure chamber 28 is inserted into the inner diameter of the connector 30 and the sub-spool 3 that slides relative to this connector 30.
It is formed between the outer diameter of 5 and the outer diameter of 5. Due to this first orifice 36, the differential pressure before and after the sub-orifice 43 becomes a high differential pressure, which is the sum of the differential pressure before and after the first orifice 36 and the differential pressure before and after the main orifice 41, and the sub-spool 35 has a low pump discharge oil amount. The opening area of the sub-orifice 43 is controlled to be reduced by driving from the flow rate range, and the discharge flow rate is effectively controlled. Therefore, even when the main spool 27 is moved to the right by the hydraulic oil that has passed through the first orifice 36 to open the drain passage 22, when the amount of pump discharged oil increases further and reaches a predetermined amount, The differential pressure generated before and after the first orifice 36, together with the differential pressure generated before and after the main orifice 41, increases the differential pressure generated before and after the sub-orifice 43, thereby moving the sub-spool 35 to the left. Therefore, the sub-orifice 43 is throttled and the amount of hydraulic oil discharged to the discharge hole 31 is reduced, and the first orifice 36 is also throttled and the amount of hydraulic oil discharged to the primary pressure chamber 28 is increased. The spool 27 is further moved to the right, and excess oil easily reaches the drain passage 22. Therefore, in the case of this embodiment, by changing the distance l from the introduction passage 25 to the tip of the sub-spool 35, an appropriate amount of hydraulic fluid is guided to the actuator, and the amount of restriction of the first orifice 36 is increased. Since the amount of oil discharged from the pump can be changed so as to decrease as the amount of oil discharged from the pump increases, excess oil when the amount of oil discharged from the pump increases is transferred to the first orifice where the flow resistance is reduced as the amount of oil discharged from the pump increases. 36 to reach the drain passage 22. In this way, the pump 1 is not forced to increase its pressure unnecessarily, that is, it is possible to advantageously avoid an unnecessary increase in the temperature of the hydraulic oil and its accompanying deterioration.

Further, the vibration of the sub-spool 35 caused by the action of the pump discharge pressure containing pulsation is suppressed by the damper chamber 37 which passes through the first orifice 36 and communicates with the downstream where the pulsation is somewhat reduced. Fluctuations in the controlled flow rate caused by the vibration of the sub-spool 35 can be prevented by the damper action acting directly on the sub-spool 35.

Furthermore, the sub-spool accommodation hole 33 provided in the connector 30 has its large diameter portion 33a connected to the primary pressure chamber 28.
Since the small diameter portion 33b is placed on the side of the communication hole 32, the sub-spool accommodation hole 33 can be placed on the opposite side without affecting the side where the discharge hole 31 for guiding hydraulic fluid to the actuator is provided. That is, it is possible to pressurize the primary pressure chamber 28 from the open end side. Therefore, the manner of connection to the actuator can be selected from a wide range of options, such as integrating the nipple 48, which was provided separately in the embodiment shown in FIG. 3, with the connector 30.

Although an example is shown in which the outer diameter of the sub-spool 35 is reduced when forming the first orifice 36, the present invention is not limited to this, and the inner diameter of the open end of the connector 30 may be increased. Further, the stopping means 40 is configured to stop the connector 30
Various modifications are possible, such as press-fitting and fixing other members into the open end of the tube.

FIG. 4 is a sectional view showing a second embodiment of the present invention. This is mainly different from the embodiment shown in FIG. The connector 30A is provided with a damping orifice 38A that opens into the damper chamber 37 and is connected to a passage 45 provided in the housing 24. Further, the connector 30A is provided with a discharge hole 31A having a female thread 31'A by expanding the diameter of the communication hole 32A. Note that the configuration other than the above is the same as the embodiment shown in FIG. 3, so the same components are denoted by the same reference numerals, and redundant explanation thereof will be omitted.

Even with this configuration, in addition to obtaining the same effect as in the above embodiment, since the outer diameter of the tip of the sub-spool 35A is tapered, the amount of contraction of the first orifice 36 due to the movement of the sub-spool 35A is reduced. By making the change larger, the responsiveness of each spool 27, 35A to a change in pump discharge amount is increased.

FIG. 5 is a sectional view showing a third embodiment of the invention. In this embodiment, the sub-spool spring 39 housed in the damper chamber 37 in FIGS. The through hole 4 provided in the body of the sub spool in each of the above embodiments
2, an oblique through hole 42B facing the introduction passage 25 is bored in the body of the connector 30B, and this is opened into the small diameter part 33b of the sub spool accommodation hole 33, so that the body of the small diameter part 35b of the sub spool 35 is opened. A sub-orifice 43B with a variable aperture is formed between the two parts. In addition, the connector 30B has a discharge hole 3.
1B is formed with a female thread 31'B, and a fuel rule 62 is press-fitted into the diameter-reduced stepped portion 61. Furthermore, a radial hole 63 is provided that opens in the small diameter portion 33b of the sub-spool accommodation hole 33, and this is communicated with the passage 45. It has been done. Note that the configuration other than the above is the same as the embodiment shown in FIG. 3, so the same components are denoted by the same reference numerals, and redundant explanation thereof will be omitted.

Even with this configuration, the same effects as described in the embodiment shown in FIG. 3 can be obtained. Also, Ferrule 6
2, it becomes possible to use a conduit whose end is so-called flared as piping from the discharge hole 31B to the actuator.

FIG. 6 is a sectional view showing a fourth embodiment of the invention. In this embodiment, the sub-orifice 4
3C is a through hole 4 that passes through the body of the large diameter portion 33a of the sub spool accommodation hole 33 provided in the connector 30C.
2C and the large diameter portion 35 of the sub spool 35 which is coaxially arranged with respect to the through hole 42C in the illustrated state.
It is formed by a through hole 42'C passing through the hole 42'C in the radial direction. Also, connector 30C
A male thread 31'C coaxial with the discharge hole 31C is formed. Note that the configuration other than the above is the same as the embodiment shown in FIGS. 3 and 5, so the same components are denoted by the same reference numerals, and redundant explanation thereof will be omitted.

Even with this configuration, substantially the same effects as in each of the embodiments described above can be obtained.

(Effects of the Invention) As described in detail above, according to the present invention, a large diameter portion and a small diameter portion are provided in a sub-spool accommodation hole formed in the hollow interior of a hollow connector, which includes a large diameter portion and a small diameter portion. A sub-spool with a section is slidably inserted into the sub-spool, and a first orifice is formed between the outer diameter of the sub-spool and the inner diameter of the connector. When the amount reaches a predetermined amount, a predetermined pressure difference is generated before and after the first orifice, which, together with the pressure difference before and after the main orifice, increases the pressure difference before and after the sub-orifice and generates a driving force to move the sub-spool. In addition to adjusting the amount of hydraulic oil that passes from the introduction passage to the discharge hole, when the amount of pump discharged oil increases further, the restriction of the first orifice is weakened to increase the amount of oil introduced into the primary pressure chamber, and the main spool is moved significantly. Excess oil can easily pass through the drain passage. Therefore, the pump discharge pressure is not increased unnecessarily, and the load on the pump is reduced.

In addition, a damper chamber is formed between the small diameter part of the connector and the large diameter part of the sub-spool, the inside of which communicates with the downstream side of the first orifice via the damping orifice. The vibration of the sub-spool caused by this is absorbed by the damper action of the damper chamber, and stable control flow characteristics can be obtained.

Furthermore, since the large diameter part of the sub-spool accommodation hole formed in the connector is opened to the primary pressure chamber, and the small diameter part is placed on the side of the communication hole leading to the discharge hole, the machining of this sub-spool accommodation hole is done on the discharge hole side of the connector. This is possible without affecting the actuator in any way, and it is possible to select a wide variety of connection modes to the actuator.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing a conventional flow control valve, Figure 2 is a sectional view showing a conventional flow control valve.
FIG. 3 is a cross-sectional view showing one embodiment of the present invention, and FIGS. 4 to 6 show second, third, and fourth embodiments of the present invention. FIG. 21...Pump, 22...Drain passage, 24...Housing, 25...Introduction passage, 26...Main spool accommodation hole, 27...Main spool, 28...Primary pressure chamber, 29...Secondary pressure chamber, 30, 30A, 30B,
30C... Connector, 31... Discharge hole, 32... Communication hole, 33... Sub spool accommodation hole, 33a... Large diameter part, 33b... Small diameter part, 34... Passage, 35... Sub spool, 35a... Large diameter part, 35b... Small diameter Part, 36
...First orifice, 37... Damper chamber, 38... Damping orifice, 39... Spring for sub-spool, 41... Main orifice, 43, 43B, 4
3C...Sub orifice, 46...Spring for main spool.

Claims (1)

[Claims] 1. In a flow control device that guides the required flow rate of the hydraulic oil discharged from the pump to the actuator and returns the excess oil flow rate with respect to the required flow rate to the drain passage, the main passage where the hydraulic oil introduction passage and the drain passage are opened is used. A main spool for controlling the surplus oil flow rate is slidably accommodated in the spool accommodation hole, and the interior of the accommodation hole is divided into a primary pressure chamber and a secondary pressure chamber, facing the primary pressure chamber, The other end of a hollow connector is opened at one end and has a discharge hole that guides hydraulic oil to the actuator, and the connector has a communication hole that communicates with the discharge hole in the hollow interior, and a large diameter part and a small diameter part. The large diameter part opens into the primary pressure chamber and the small diameter part is located on the side of the communication hole. A passage is provided in the sub-spool accommodation hole to communicate with the large diameter part of the sub-spool accommodation hole. A shaped sub-spool is slidably inserted into the sub-spool so that one end of the large-diameter side of the sub-spool faces the primary pressure chamber, and the outer diameter of the one end of the sub-spool is equal to the inner diameter of the large-diameter portion of the connector. A first orifice is formed between the small diameter portion of the connector and the large diameter portion of the sub spool to change the amount of restriction of the hydraulic oil introduced from the introduction passage to the primary pressure chamber as the sub spool slides. A damper chamber whose contents communicate with the downstream side of the first orifice via a damping orifice is formed between the damper chamber and the damper chamber, and the hydraulic fluid that has passed through the first orifice is introduced into the hollow interior of the sub-spool. A main orifice is provided to communicate with the communication hole of the connector, while a sub-orifice with a variable throttle is provided in an oil path between the introduction passage and the communication hole of the connector and is arranged in parallel with the main orifice, The discharge pressure of the pump is introduced into the introduction passage, the pressure of the hydraulic oil that has passed through the first orifice is transferred to the primary pressure chamber, and the pressure of the hydraulic oil that has passed through the main orifice and sub-orifice is transferred to the secondary pressure chamber. By guiding each of them, a differential pressure is applied to the main spool before and after the main orifice, and by increasing this differential pressure, the opening area of the drain passage is increased, and a spring for the main spool counteracts this differential pressure. By energizing the main spool and introducing the discharge pressure of the pump into the introduction passage, the first
The differential pressure between the orifice, the main orifice, and the sub-orifice is applied, and by increasing this differential pressure, the degree of constriction of the sub-orifice is strengthened, and the degree of constriction of the first orifice is loosened. A flow control device in which a sub-spool spring biases the sub-spool in opposition.